Alternator Woes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ol Curt · 11-09-2009, 02:55 PM

My generator lite was staying on in my factory dash on my 66 truck. I found the old alternator saturated with p.s. fluid. It seems one of the fittings was leaking, and the alternator was soaked.

Whether it was bad or not, I decided it would be a great time to upgrade to an internally regulated alternator.
I followed as many of the instructions I could find...bought one for a 78 Camaro w/350. This gave me a 10 SI clocked the way I needed it. I also bought the plug for it.
I wired this just as the instructions say and when I started the truck...generator light is still on. When I revved it a bit, I found the "Bright" light signaling high beams lit up...but no high beams were on.

Any ideas where I begin to diagnose this?

This is the info I used. http://67-72chevytrucks.com/vboard/a.../t-119379.html

ol Curt · 11-09-2009, 08:07 PM

I posted this over in the electrical forum as well. I'm hoping between the two somebody will offer some words of wisdom. It did occur to me that the battery is low. Would that cause the gen light to stay on till it was charged?

ol Curt · 11-09-2009, 09:17 PM

Ok, it gets weirder as I go. I put a quick charge on the battery and started the truck. I checked the voltage at the battery when running and it was 14 volts...(probably ok).

The dim lights don't work at all when switch is on, but the "bright" light and the "gen" light are both still on. When I hit the dimmer switch, the bright lights come on. I haven't remounted my dimmer switch after installing carpet, but I did ground it to a known ground with no success.

One step forward, two steps back...this dance is getting old!

OK, I guess one last question...should the alternator have a ground wire on it?

ol Curt · 11-09-2009, 10:13 PM

I checked for voltage at the terminal number 1 with the key on and there was none, which might start to explains some things. But, now I'm not sure where to go.

Also found no voltage at firewall connector with key on. Unfortunately I am out of time tonight. I think I will be pulling the cluster out tomorrow.

11-09-2009, 02:55 PM	#1
ol Curt Junior Member Join Date: Dec 2006 Location: Newburgh, IN Posts: 1,247	Alternator Woes My generator lite was staying on in my factory dash on my 66 truck. I found the old alternator saturated with p.s. fluid. It seems one of the fittings was leaking, and the alternator was soaked. Whether it was bad or not, I decided it would be a great time to upgrade to an internally regulated alternator. I followed as many of the instructions I could find...bought one for a 78 Camaro w/350. This gave me a 10 SI clocked the way I needed it. I also bought the plug for it. I wired this just as the instructions say and when I started the truck...generator light is still on. When I revved it a bit, I found the "Bright" light signaling high beams lit up...but no high beams were on. Any ideas where I begin to diagnose this? This is the info I used. http://67-72chevytrucks.com/vboard/a.../t-119379.html __________________ 1966 Chevy C10 Longbed I'm Bob....ol Curt was my Grandpa The truck was his and he sure as heck wouldn't understand why I took a perfectly good truck and tore it down! Last edited by ol Curt; 11-09-2009 at 03:02 PM.

11-09-2009, 08:07 PM	#2
ol Curt Junior Member Join Date: Dec 2006 Location: Newburgh, IN Posts: 1,247	Re: Alternator Woes I posted this over in the electrical forum as well. I'm hoping between the two somebody will offer some words of wisdom. It did occur to me that the battery is low. Would that cause the gen light to stay on till it was charged? __________________ 1966 Chevy C10 Longbed I'm Bob....ol Curt was my Grandpa The truck was his and he sure as heck wouldn't understand why I took a perfectly good truck and tore it down!

11-09-2009, 09:17 PM	#3
ol Curt Junior Member Join Date: Dec 2006 Location: Newburgh, IN Posts: 1,247	Re: Alternator Woes Ok, it gets weirder as I go. I put a quick charge on the battery and started the truck. I checked the voltage at the battery when running and it was 14 volts...(probably ok). The dim lights don't work at all when switch is on, but the "bright" light and the "gen" light are both still on. When I hit the dimmer switch, the bright lights come on. I haven't remounted my dimmer switch after installing carpet, but I did ground it to a known ground with no success. One step forward, two steps back...this dance is getting old! OK, I guess one last question...should the alternator have a ground wire on it? __________________ 1966 Chevy C10 Longbed I'm Bob....ol Curt was my Grandpa The truck was his and he sure as heck wouldn't understand why I took a perfectly good truck and tore it down! Last edited by ol Curt; 11-09-2009 at 09:43 PM.

11-09-2009, 10:13 PM	#4
ol Curt Junior Member Join Date: Dec 2006 Location: Newburgh, IN Posts: 1,247	Re: Alternator Woes I checked for voltage at the terminal number 1 with the key on and there was none, which might start to explains some things. But, now I'm not sure where to go. Also found no voltage at firewall connector with key on. Unfortunately I am out of time tonight. I think I will be pulling the cluster out tomorrow. __________________ 1966 Chevy C10 Longbed I'm Bob....ol Curt was my Grandpa The truck was his and he sure as heck wouldn't understand why I took a perfectly good truck and tore it down! Last edited by ol Curt; 11-09-2009 at 10:54 PM.

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